HOW TO WASTE A REALLY LOT OF TIME WITHOUT REALLY TRYING
and a little bit of money too
With Pics!
I assiduously avoid riding at night (driving too), however I recently found myself riding home in the dark, and I became acutely aware of how much my original, stock headlight on the 1973 TX650 Super Rustbucket sucks.
There are already at least a couple of threads with early headlight retrofit solutions:
https://www.xs650.com/threads/finally-finished-tx-tidy-up.69690/page-2#post-909263 post #35
and:
https://www.xs650.com/threads/xsb-1-650-retard-new-headlight-project.61515/#post-735221 post #9
and:
https://www.xs650.com/threads/xsb-1-650-retard-new-headlight-project.61515/#post-735380 post #18
These are great solutions, but none is perfect. I thought I could do better (I couldn't).
I've read a lot about how wonderful LED upgrades are, so I thought that was the way to go (spoiler alert, it isn't).
Following is my journey, and the recycled solution I ultimately settled on.
This is the back of an original, stock 1970-1973 sealed beam headlight.
This burned out unit was my donor. MARK THE ORIENTATION of the connector blades. Pry the tabs up, remove the metal retaining ring, and grab, twist, and pull the bulb base out. The bulb glass will break off and remain inside the sealed beam. There is a metal flange (or fin) soldered around the bulb base, and a black rubber grommet/washer around the flange.
My rubber grommet was very stuck to the flange. I had to work a small bent pick all the way around the flange to free it before I could pull the bulb base out.
Save the metal retaining ring and the rubber grommet. Use a rod to break the glass bulb into pieces that are small enough to fall out of the bulb hole. Blow out the inside of the sealed beam, and if necessary, clean the inside surface of the sealed beam lens with a damp cloth wrapped around a dowel inserted into the bulb hole.
The task I now set out for myself was to find a flanged bulb that would fit into the original bulb hole WITHOUT ALTERING THE FLANGE and WITHOUT ENLARGING THE BULB HOLE in the back of the sealed beam.
Figure 1. These are just some of the bulbs I looked at. All are dual filament. All of them fit into the bulb hole without enlarging it (the H4 LED only inserts half way). Also, the H4 bulbs need to have their flanges trimmed, which we will get to.
The PX15d bulbs fit in a pinch, but aren't really suitable because their maximum wattage is only 35/35, and their focal length (which we'll get to) is wrong.
BTW, I have used 6 volt versions of the PX15d to retrofit scores of the rare-as-hell Suzuki TS185 flat-bottom headlight. This was sort of a minor cottage industry of mine for a while. These are always burned out because the TS185 uses the battery as a voltage regulator, and when the battery dies you have no regulation, but the bike still starts because it has a magneto, and you blow out all the lights. I have also used 6 volt PX15d's to retrofit burned out Honda Express NC50 scooter headlights, which likewise have a magneto and use the battery as a regulator.
This is a P15D-30.
Fun Fact: A 6 volt P15D-30 is used in the optional TT500 headlight kit, and a few other 60's and 70's Yamaha dirt bikes.
This is an LED P15D-30. I thought this was the perfect solution, and I bought a pair for $20 plus tax. It fits into the bulb hole, and the flange is only slightly smaller than the original stock flange.
However, I discovered that all 6 LEDs on each side light up on "LO" beam, and that they merely get brighter on "HI" beam. It isn't a true HI/LO bulb. And the focal length (which I'm still going to get to), is wrong. This was the only LED P15D-30 that fit the bulb hole.
The P15D-30 is not a very common bulb, and there weren't too many LED versions to choose from. Here's another reject. Won't fit in the bub hole, not a true HI/LO bulb, and the focal length is wrong. The strategy of bulbs like this is: damn the focal length, we're just gonna emit as much light as possible, and hope that some of it goes in the right places, and oncoming drivers can go to hell.
Speaking of totally bogus LED bulbs, this video has some interesting info. Not motorcycle or dual-filament specific, but the 3:00 to 10:30 minute mark has good info on what to look for regarding LED bulb design and on LED heat sinks.
Fun Fact #2: The P15D-30 is also known as an APF, which stand for American Pre-Focus. The PX15d is sometimes called a MPF, which stand for Miniature Pre-Focus. Neither to be confused withe BPF, which stands for British Pre-Focus, and which is too big to be a candidate for the 1970-73 headlight retrofit.
Speaking of focus...
Your headlight is supposed to send a FOCUSED beam of light down the road, something like this drawing.
This is accomplished by placing the filament in a PRECISE location within a PARABOLIC reflector.
Which brings us to the H4 bulb. Because we destroyed the tungsten filament when we removed the stock original bulb from the sealed beam, we don't exactly know what the correct HI and LO beam focal lengths are. But, based on my research, I think the H4 is pretty close to original.
At this point, I still thought LEDs were the way, so I bought the LED H4 above for $25.97, shipped. I quickly realized that the bulb hole in the sealed beam would have to be enlarged, and that trimming down the flange would be crazy. So, another reject.
I'll also mention that I am not 100% confident that if one "element" of an LED dual filament bulb burns out that the other will still work. For example if you have a cooling fan failure, both elements will fail in quick succession. On a car, no problem, you have another headlight. On a motorcycle, it is essential that you always have a back-up beam in the case of an element failure.
Onwards to this Halogen H4 bulb that I bought for the bargain price of $10.67, delivered. NOS on eBay. I like it so much that I am going to buy a couple more. It even says "For Motorcycle Use Only" right on the package. I have no idea what that means, but it can't hurt.
The reason I chose the Sylvania H4 is because, based on images, I though there was a good probability that it would fit. There is no way that the above H4 with the wide collar shown would fit the bulb hole in the sealed beam.
Here I used a Dremel cut-off wheel to cut some of the flange off. I sleeved the bulb with a piece of heat-shrink tubing (which I did NOT shrink) so that I wouldn't be touching the glass.
I finished trimming the flange to size on a bench grinder. This was somewhat nerve-wracking.
Placed the rubber grommet around the flange, and the bulb is ready to install.
Finished retrofit.
and a little bit of money too
With Pics!
I assiduously avoid riding at night (driving too), however I recently found myself riding home in the dark, and I became acutely aware of how much my original, stock headlight on the 1973 TX650 Super Rustbucket sucks.
There are already at least a couple of threads with early headlight retrofit solutions:
https://www.xs650.com/threads/finally-finished-tx-tidy-up.69690/page-2#post-909263 post #35
and:
https://www.xs650.com/threads/xsb-1-650-retard-new-headlight-project.61515/#post-735221 post #9
and:
https://www.xs650.com/threads/xsb-1-650-retard-new-headlight-project.61515/#post-735380 post #18
These are great solutions, but none is perfect. I thought I could do better (I couldn't).
I've read a lot about how wonderful LED upgrades are, so I thought that was the way to go (spoiler alert, it isn't).
Following is my journey, and the recycled solution I ultimately settled on.
This is the back of an original, stock 1970-1973 sealed beam headlight.
This burned out unit was my donor. MARK THE ORIENTATION of the connector blades. Pry the tabs up, remove the metal retaining ring, and grab, twist, and pull the bulb base out. The bulb glass will break off and remain inside the sealed beam. There is a metal flange (or fin) soldered around the bulb base, and a black rubber grommet/washer around the flange.
My rubber grommet was very stuck to the flange. I had to work a small bent pick all the way around the flange to free it before I could pull the bulb base out.
Save the metal retaining ring and the rubber grommet. Use a rod to break the glass bulb into pieces that are small enough to fall out of the bulb hole. Blow out the inside of the sealed beam, and if necessary, clean the inside surface of the sealed beam lens with a damp cloth wrapped around a dowel inserted into the bulb hole.
The task I now set out for myself was to find a flanged bulb that would fit into the original bulb hole WITHOUT ALTERING THE FLANGE and WITHOUT ENLARGING THE BULB HOLE in the back of the sealed beam.
Figure 1. These are just some of the bulbs I looked at. All are dual filament. All of them fit into the bulb hole without enlarging it (the H4 LED only inserts half way). Also, the H4 bulbs need to have their flanges trimmed, which we will get to.
The PX15d bulbs fit in a pinch, but aren't really suitable because their maximum wattage is only 35/35, and their focal length (which we'll get to) is wrong.
BTW, I have used 6 volt versions of the PX15d to retrofit scores of the rare-as-hell Suzuki TS185 flat-bottom headlight. This was sort of a minor cottage industry of mine for a while. These are always burned out because the TS185 uses the battery as a voltage regulator, and when the battery dies you have no regulation, but the bike still starts because it has a magneto, and you blow out all the lights. I have also used 6 volt PX15d's to retrofit burned out Honda Express NC50 scooter headlights, which likewise have a magneto and use the battery as a regulator.
This is a P15D-30.
Fun Fact: A 6 volt P15D-30 is used in the optional TT500 headlight kit, and a few other 60's and 70's Yamaha dirt bikes.
This is an LED P15D-30. I thought this was the perfect solution, and I bought a pair for $20 plus tax. It fits into the bulb hole, and the flange is only slightly smaller than the original stock flange.
However, I discovered that all 6 LEDs on each side light up on "LO" beam, and that they merely get brighter on "HI" beam. It isn't a true HI/LO bulb. And the focal length (which I'm still going to get to), is wrong. This was the only LED P15D-30 that fit the bulb hole.
The P15D-30 is not a very common bulb, and there weren't too many LED versions to choose from. Here's another reject. Won't fit in the bub hole, not a true HI/LO bulb, and the focal length is wrong. The strategy of bulbs like this is: damn the focal length, we're just gonna emit as much light as possible, and hope that some of it goes in the right places, and oncoming drivers can go to hell.
Fun Fact #2: The P15D-30 is also known as an APF, which stand for American Pre-Focus. The PX15d is sometimes called a MPF, which stand for Miniature Pre-Focus. Neither to be confused withe BPF, which stands for British Pre-Focus, and which is too big to be a candidate for the 1970-73 headlight retrofit.
Speaking of focus...
Your headlight is supposed to send a FOCUSED beam of light down the road, something like this drawing.
This is accomplished by placing the filament in a PRECISE location within a PARABOLIC reflector.
Which brings us to the H4 bulb. Because we destroyed the tungsten filament when we removed the stock original bulb from the sealed beam, we don't exactly know what the correct HI and LO beam focal lengths are. But, based on my research, I think the H4 is pretty close to original.
At this point, I still thought LEDs were the way, so I bought the LED H4 above for $25.97, shipped. I quickly realized that the bulb hole in the sealed beam would have to be enlarged, and that trimming down the flange would be crazy. So, another reject.
I'll also mention that I am not 100% confident that if one "element" of an LED dual filament bulb burns out that the other will still work. For example if you have a cooling fan failure, both elements will fail in quick succession. On a car, no problem, you have another headlight. On a motorcycle, it is essential that you always have a back-up beam in the case of an element failure.
Onwards to this Halogen H4 bulb that I bought for the bargain price of $10.67, delivered. NOS on eBay. I like it so much that I am going to buy a couple more. It even says "For Motorcycle Use Only" right on the package. I have no idea what that means, but it can't hurt.
The reason I chose the Sylvania H4 is because, based on images, I though there was a good probability that it would fit. There is no way that the above H4 with the wide collar shown would fit the bulb hole in the sealed beam.
Here I used a Dremel cut-off wheel to cut some of the flange off. I sleeved the bulb with a piece of heat-shrink tubing (which I did NOT shrink) so that I wouldn't be touching the glass.
I finished trimming the flange to size on a bench grinder. This was somewhat nerve-wracking.
Placed the rubber grommet around the flange, and the bulb is ready to install.
Finished retrofit.
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